This is the Multiple Choice Questions (MCQs) in Chapter 15: Impedance and Admittance from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco. If you are looking for a reviewer in Electronics Engineering this will definitely help you before taking the Board Exam.
Start Practice Exam Test Questions
1. The square of an imaginary number:
- A. Can never be negative.
- B. Can never be positive.
- C. Might be either positive or negative.
- D. Is equal to j.
2. A complex number:
- A. Is the same thing as an imaginary number.
- B. Has a real part and an imaginary part.
- C. Is one-dimensional.
- D. Is a concept reserved for elite imaginations.
3. What is the sum of 3 + j7 and 3 - j7?
- A. 0 + j0
- B. 6 + j14.
- C. -6 - j14.
- D. 0 - j14.
4. What is (-5 + j7) - (4 - j5)?
- A. -1 + j2.
- B. -9 - j2.
- C. -1 - j2.
- D. -9 + j12.
5. What is the product (-4 - j7) (6 - j2)?
- A. 24 - j14.
- B. -38 - j34.
- C. -24 - j14.
- D. -24 + j14.
6. What is the magnitude of the vector 18 - j24?
- A. 42.
- B. -42.
- C. 30.
- D. -30.
7. The impedance vector 5 + j0 represents:
- A. A pure resistance.
- B. A pure inductance.
- C. A pure capacitance.
- D. An inductance combined with a capacitance.
8. The impedance vector 0 - j22 represents:
- A. A pure resistance.
- B. A pure inductance.
- C. A pure capacitance.
- D. An inductance combined with a resistance.
9. What is the absolute-value impedance of 3.0 - j6.0?
- A. Z = 9.0 Ω.
- B. Z = 3.0 Ω.
- C. Z = 45 Ω.
- D. Z = 6.7 Ω.
10. What is the absolute-value impedance of 50 - j235?
- A. Z = 240 Ω.
- B. Z = 58,000 Ω.
- C. Z = 285 Ω.
- D. Z = 185 Ω.
11. If the center conductor of a coaxial cable is made to have smaller diameter, all other things being equal, what will happen to the Zo of the transmission line?
- A. It will increase.
- B. It will decrease.
- C. It will stay the same.
- D. There is no way to know.
12. If a device is said to have an impedance of Z = 100 Ω, this would most often mean that:
- A. R + jX =100 + j0.
- B. R + jX = 0 + j100.
- C. R + jX = 0 - j100.
- D. You need to know more specific information.
13. A capacitor has a value of 0.050 μF at 665 kHz. What is the capacitive susceptance?
- A. j4.79.
- B. -j4.79.
- C. j0. 209.
- D. -j0. 209.
14. An inductor has a value of 44 mH at 60 Hz. What is the inductive susceptance?
- A. -j0.060.
- B. j0.060.
- C. -j17.
- D. j17.
15. Susceptance and conductance add to form:
- A. Impedance.
- B. Inductance.
- C. Reactance.
- D. Admittance.
16. Absolute-value impedance is equal to the square root of:
- A. G2 + B2
- B. R2 + X2.
- C. Zo.
- D. Y.
17. Inductive susceptance is measured in:
- A. Ohms.
- B. Henrys.
- C. Farads.
- D. Siemens.
18. Capacitive susceptance is:
- A. Positive and real valued.
- B. Negative and real valued.
- C. Positive and imaginary.
- D. Negative and imaginary.
19. Which of the following is false?
- A. BC = 1/XC.
- B. Complex impedance can be depicted as a vector.
- C. Characteristic impedance is complex.
- D. G = 1/R.
20. In general, the greater the absolute value of the impedance in a circuit:
- A. The greater the flow of alternating current.
- B. The less the flow of alternating current.
- C. The larger the reactance.
- D. The larger the resistance.
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